RT Book, Section A1 Sathiyakumar, Vasanth A1 Jones, Steven R. A1 Martin, Seth S. A2 Kang, Sewon A2 Amagai, Masayuki A2 Bruckner, Anna L. A2 Enk, Alexander H. A2 Margolis, David J. A2 McMichael, Amy J. A2 Orringer, Jeffrey S. SR Print(0) ID 1161338650 T1 Xanthomas and Lipoprotein Disorders T2 Fitzpatrick's Dermatology, 9e YR 2019 FD 2019 PB McGraw-Hill Education PP New York, NY SN 9780071837798 LK accessmedicine.mhmedical.com/content.aspx?aid=1161338650 RD 2024/10/15 AB AT-A-GLANCEXanthomas are plaques or nodules consisting of an abnormal excess of lipid primarily in the skin or tendons.Clinically, xanthomas may be divided into eruptive, tuber-eruptive or tuberous, tendinous, or planar forms. Two traditionally noninherited variations include verruciform and disseminated xanthomas, both of which have a propensity for largely noncutaneous manifestations.Xanthomas are not disease entities themselves but are signs of various lipoprotein disorders, which may be primary lipid disorders or secondary disorders from a variety of causes including hepatic, hematologic, and endocrine sources.The key pathogenesis of xanthoma formation consists of the downstream formation of foam cells, which involves an interplay of various lipoproteins including chylomicrons, very-low-density lipoproteins (VLDLs), chylomicron and VLDL remnant lipoproteins, low-density lipoproteins, and high-density lipoproteins.Primary dyslipidemias, designated as Types I to V, have been historically categorized into various phenotypes described by Fredrickson, Levy, and Lees, based on the elevated lipoprotein fractions found in serum.Diagnosis of xanthoma is based on clinical and morphologic characteristics of the lesions and identifying the underlying lipid disorder.Treatment of xanthoma is aimed at the underlying lipid disorder, and typically involves lifestyle changes (diet, weight loss, smoking cessation) and medications (statins, adjuvant agents, PCSK9 inhibitors).Young patients with xanthomas and those with suspected familial dyslipidemias should be referred for genetic testing and counseling.